Conventionally, in the development of a plant represented by a water supply and sewerage system, control logic diagrams in which an operation plan defining operation specifications of devices is described by flowcharts and logical operators have widely been used. However, in the development of a plant, hundreds of control logic diagrams are often necessary for the description, and efficient creation of them has been desired.
Patent Literature 1, which is an example of a conventional technique, discloses a logic diagram search device that searches a similar logic included in another diagram for a logic described in a control logic diagram, using logical connection information and position information of signals and computation elements in the control logic diagram, and renders a control logic having high appearance frequency as a part, thereby making it possible to improve maintainability and productivity.